BUCHI NIRFlex N-500 - Manual (Page 22)

4 Description of function
22 NIRFlex N-500 Operation Manual, Version F
NOTE
With special accessories, reflection-mode probes can be equipped for transflectance. •
The samples should either be measured at a constant temperature or the temperature influences •
must be considered during calibration.
Recommended number of scans:
• Qualitative calibration: 4−16; quantitative calibration: 16−32
Most liquid sample materials can be constantly analyzed with the help of a flow-cell adapter. •
4 .2 .2 Diffuse reflection mode
Most non-translucent materials (e.g. solids such as powders, pellets and cereals) can be analyzed
via diffuse reflection. The NIR light penetration is limited by the sample material. It interacts with the
sample, is refracted and diffusely reflected into the sensor. The reflected rays contain the spectral
information of the sample.
Detector
NIR light
Sample material
Factors that can influence the measurement:
Not enough sample material available •
Sample not homogenious or representative •
Humidity of sample material •
Temperature of sample material •
Sample cup inadeqate (e.g. cup material and thickness, blind spots, dirt etc.) •
NOTE
The samples should either be measured at a constant temperature or the temperature influences •
must be considered during calibration.
Coarse grained samples should be milled before carrying out the measurement. Recommended
•
number of scans: Qualitative calibration: 4−16; quantitative calibration: 16−32;
granules: 64.